Chemopreventive Potential of Aloe vera Against 7,12-Dimethylbenz(a)anthracene— Induced Skin Papillomagenesis in Mice

The present investigation was undertaken to explore the antitumor-promoting activity of Aloe vera on 2-stage skin carcinogenesis, induced by a single topical application of 7,12-dimethylbenz(a)anthracene and promoted by treatment of croton oil for 16 weeks in Swiss albino mice. Oral administration of aloe leaf extract at a dose of 1000 mg/kg body weight/d and aloe gel treatment at a dose of 1 mL/ 9 cm 2 /mice/d was found to be effective in decreasing the number and size of the papillomas. A significant reduction in tumor incidence (40.00 ± 5.10, 30.00 ± 3.25, and 40.00 ± 4.12 for aloe gel, aloe gel and aloe leaf extract combined, and aloe leaf extract alone, respectively) was observed in animals in the aloe extract— and aloe gel—treated groups compared with 100% tumor incidence in the control group. The cumulative number of papillomas during an observation period of 16 weeks was significantly reduced in the aloe-treated groups (8.0 ± 0.34, 6.00 ± 1.10, and 9.00 ± 1.41 for aloe gel, aloe gel and leaf extract, and aloe leaf extract, respectively) compared with a 36 ± 0.98 cumulative number of papillomas in the control group. The average latent period was significantly increased from 4.9 ± 0.10 weeks in the control group to 6.37 ± 0.12, 6.8 ± 0.25, and 6.2 ± 0.21 weeks in the aloe-treated groups, respectively. The tumor burden and tumor yield were significantly decreased (2.0 ± 0.25, 2.00 ± 0.30, and 2.25 ± 0.2 and 0.8 ± 0.25, 0.6 ± 0.32, and 0.9 ± 0.28, respectively) as compared with the 7,12-dimethylbenz(a)anthracene—treated control group (3.6 ± 0.10 and 3.6 ± 0.19). Furthermore, treatment with aloe gel and/or extract by topical and/or oral administration resulted in a significant increase in the reduced glutathione ( P < .05), DNA ( P < .001), catalase ( P < .05), and protein ( P < .001) in the skin of mice. Conversely, lipid peroxidation levels were significantly decreased ( P < .001) in the skin of mice.